"We were still ascending when we made Brain Salad Surgery," Keith Emerson says. "We were enjoying a sensational amount of success, and I suppose we felt as if we could do anything – and we certainly tried. Musically, lyrically and visually, we really went for it."

The album would be the inaugural release by the band's newly formed Manticore label and would differ from the extensively overdubbed Trilogy in that the group plotted out the music as a largely live creation. At the start of 1973, Emerson, Greg Lake and Carl Palmer purchased an abandoned cinema in Fulham, London, and converted it into a rehearsal and production facility, using an upstairs foyer to assemble and run through new compositions.

“That was the general idea, to play the album live," Emerson recalls. "I pretty much had the whole concept in mind. We had taken a bit of a break to be with our families, so that gave me a fair enough time to put down enough hand-written ideas for the Karn Evil 9. I then approached Greg and Carl with a sheaf of manuscript papers, and we set about rehearsing, going over the material and being sort of repetitive about it."

Once the epic Karn Evil 9 was worked out – the 30-minute sci-fi tale of man vs machine would spill over from side one and encompass the whole of side two – ELP loosened up with the deliciously lighthearted honky-tonk saloon spoof Benny The Bouncer. "We liked to get the serious stuff out of the way and then do something fun," Emerson says. "We had done Are You Ready Eddy? and The Sheriff before. It was always a nice little breather to soften the mood, both in the studio and on record."

To complete the lyrics to both Karn Evil 9 and Benny The Bouncer, Lake recruited his old pal and former King Crimson bandmate Peter Sinfield. "Greg had always been a prolific songwriter and lyricist," Emerson notes, "but at this particular time he needed the influence of somebody he had confidence in. Pete brought a lot of fantastic ideas and lines to the songs.”

Recording took place between June and September of 1973 at London's Advision and Olympic Studios, with Lake, as he had done on the group's previous albums, serving as producer. "It was a pretty straightforward time in the studio," Emerson says, "even with some of the new pieces of equipment we were using, like the Moog Apollo. Because we were so rehearsed, there wasn't a lot of mucking about. We didn’t have Pro Tools and all the things that exist now. If a person made a mistake, you didn’t say, ‘Oh, we’ll fix that later.’ We really had to get it right as we played together."

Originally, the album was to be called Whip Some Skull On Ya – a slang expression for fellatio. The eventual title of Brain Salad Surgery, nicked from a lyric in Dr. John's hit Right Place, Wrong Time, dismayed artist H.R. Giger, who had been commissioned by Emerson to create the jarring and groundbreaking cover art. When Emerson explained that Brain Salad Surgery carried the same connotation as Whip Some Skull On Ya, Giger was greatly relieved.

By the decade's end, Giger's work would become famous from the film Alien, but in 1973 he was still regarded as something of an underground artist. Emerson had been made aware of the Swiss surrealist by Manticore's Peter Zumsteg, who drove the keyboardist to meet with Giger at his Zurich studio. "The second I walked in, I was absolutely amazed," Emerson says. "The artwork represented the music we were working on as fully as I could have imagined. The next day, I told Greg and Carl, ‘You’ve got to some with me to see what this guy is doing.’ I think they were kind of reluctant at the beginning, but once they saw his stuff, they were incredibly intrigued. I’m so pleased with where we went for the cover. I think it’s one of the best pieces of album art I’ve ever seen, to be honest."

The across-the-board success of Brain Salad Surgery – helped in large part by the nearly constant spins of Karn Evil 9's First Impression, Part 2 on FM radio – cemented Emerson, Lake & Palmer's worldwide popularity, and the group capitalized on their fame with a stage show so grandiose (over 36 tons of gear, complete with levitating, spinning keyboards and the world's first discrete quadrophonic PA system) that the only band who could top them was... Emerson, Lake & Palmer! And, sure enough, in 1977 they did just that, bringing a 70-piece orchestra on the road for the budget-busting Works tour.

On April 7, 2014, Razor & Tie will issue a three-disc 40th Anniversary Deluxe Edition of Brain Salad Surgery, which includes the remastered original album, an "alternate album" that features previously unreleased material and a DVD-A of new 5.1 mixes of the original album. You can pre-order the Deluxe Edition and various bundles of the set at elp.merchnow.com.

"It's always hard to pinpoint why a particular album hits the mark and lives on and on," Emerson muses. "Out of all our other records, this was our biggest, and even today, it’s the one that most everybody knows. It really touched a nerve with a lot of people."

On the following pages, Emerson recounts the writing and recording of Brain Salad Surgery track-by-track.